Return to Zero
by G.S.Pheonix
Summary: The last thing Kiritsugu recalled was dying. He never expected what came next. This was his chance to make things right. He would not fail.


Disclaimer:I dont own anything

Kiritsugu Emiya slowly opened his eyes, the phantom of being tired was still in his body. After some moments, he sat up. There was something different, he noticed.

For some reason, he felt stronger and healthier than he ever did in the past three years.

Was this the afterlife? No, Kiritsugu discarded that thought almost immediately. He was pretty sure that you couldn't feel stiffness after death, or so he thought.

But then again, if so then how could he be alive? He clearly recalled the last of his life slipping away as he looked at the full moon, an smile on his lips after having that conversation with his son.

Furthermore he recalled having been outside at the time, so then why was he suddenly indoors on a bed? Taking a look at his surroundings, the assassin noted it looked exactly like his old room back in those days in Germany.

"Kiritsugu," A familiar voice penetrated his ears, turning towards it, he suddenly stopped as he saw who the speaker was. Standing at the now open door, was a beautiful caucasian woman with red eyes and long snow-white hair. She wore a white dress, its tone of white was almost identical to the one of her hair, accompanied by a pair of gloves.

"Father asked me to find you. He said that the relic has been found and will arrive soon," She then paused, and looked at him with a confused look. "Is something wrong, Kiritsugu?"

But the Emiya didn't reply as he was lost in thought. She was here. Irisviel Von Einzbern, the woman he loved, was here. Was this truly the afterlife?

...No, it couldn't be. Iri mentioned a relic. Now, he could say with almost 100% of sureness that he wasn't dead. Furthermore, if this really was the afterlife he doubted that Iri would react like that at seeing him after so long.

He was pretty good hiding his emotions, but Iri wasn't. She would be jumping of excitement at seeing him were this place where souls go after one's death. He could be sure about that.

But back to she had said. If everything was the same as he remembered, the relic Iri had mentioned was none other than Avalon, the scabbard of Excalibur.

Years ago, Kiritsugu used this scabbard as a catalyst to summon the King of Knights to fight in the Fourth Holy Grail War, a battle royal in which seven Magi summoned Heroic Spirits, one per Magus, and faced each other in order to obtain the Holy Grail, a device said to be able to grant any wish.

Back then, Kiritsugu had hoped to use the Grail in order to achieve a world without suffering. It sounded like a good wish, didn't it? But when Kiritsugu finally reached the Holy Grail, he discovered the bitter truth.

The Holy Grail was cursed.

During the Third grail war, the Einzberns had tried to summon Angra Mainyu as a servant called Avenger. But what the summoned was not an evil god, but the heroic spirit of a boy who was sacrificed as a living incarnation of all the worlds evil. When he was defeated, he tainted the grail from within so that all wishes would be granted through complete genocide and destruction.

When Kiritsugu realized this, he ordered to his Servant, Saber, to destroy the Holy Grail using two of his Command Seals. Saber cursed him like very few did, but even she couldn't resist to the might of two Command Seals combined. At the end she succumbed an unleashed her Noble Phantasm, the Holy Sword Excalibur, upon the Grail, destroying it.

However, he didn't come unharmed after that. Angra Mainyu, in a form of revenge, released a fire alongside some of his better curses upon Fuyuki City, and Kiritsugu had been touched by some of the strongest curses. The effect wasn't immediate, but it was enough to reduce his life significantly. He remembered dying five years later, watching the stars alongside his adoptive son, Shirou.

Ah, there was also that. Angra Mainyu's fire destroyed a whole section of Fuyuki, killing everything and everyone in its way. Kiritsugu had walked through that hell, in search of a survivor. It took time, but he finally found one.

In the ground there was a red-haired child, his eyes unfocused and devoid of life. He remembered running to the kid, catching his little hand, not letting him die.

Kiritsugu recalled how he smiled like a child in the morning of Christmas after receiving the present they wanted, crying tears of happiness and muttering "Thank you" time and time again.

He saved the boy, and doing that, he saved himself. He implanted Avalon in the child, keeping him alive, and took him to the nearest hospital.

Eventually, he asked to the boy, who said that his name was Shirou, if he wanted to go with him or be sent to an orphanage.

Shirou took his time to answer, but he finally agreed, pointing at Kiritsugu with his finger.

They eventually came to love each other like true father and son, furthermore-

No, he was thinking too much about the past. Kiritsugu should focus on what was going on right now.

From what it seemed, he had been sent back before the war had begun. Certainly he never thought of that as a possibility.

But what's more, he could not feel that damn curse on his body, making him feel feel healthier than he ever hope to feel since the fire.

"Kiritsugu?" Iri broke his train of thought

Kiritsugu looked at his wife and realized that he had spaced out contemplating everything for more than a minute, staring at the nothing. He did that a lot recently, maybe he truly was becoming an old man.

Kiritsugu chuckled. Taiga, his neighbor's granddaughter, used to annoy him with that.

"Sorry Iri, I just realized something. Is there anything else?"

Iri looked at him bewildered for a moment, as she had seen something that she rarely did. After a moment she shook her head, a soft smile appeared on her lips.

"Yes, a package directed to you arrived a little ago. It has a seal that we can't break."

Kiritsugu nodded. "Okay then, I'll take a look at it."

* * *

Kiritsugu stared at the object in his hand.

While he didn't claim to have a perfect memory, he was certain that he never received this package before. It was a small box wrapped in paper.

The box had also been enchanted so that only he could open it, and when he did, he found a letter inside...

One which contents shocked him to say the least.

'To Kiritsugu Emiya

'I believe that you might be confused at finding yourself back in time, don't you?

'Allow me to introduce myself. I am Kischur Zelretch Schweinorg, user of the Second True Magic, the Kaleidoscope. As you might have realized by now, I'm the one responsible of your current situation.

'You may be asking to yourself, why? Well, in truth it's a pretty simple answer. Because of you, your son was given a chance to escape from his terrible fate. And when I saw that, I thought. Why don't I give you the same?

'I decided to give you a chance in changing things for the better. However, you did not truly travel back in time. What I did was use my power to give you the memories of one of your counterpart's, and sent them to you in this specific moment in this specific timeline.

'Don't worry about the details nor what I did with your counterpart, he his fine here with me!

'Anyway, I'm sure you found a card alongside this letter. It's called 'class card'.

'In another world, rather than summon Servants, Magi used these class cards to infuse themselves with a portion of a Heroic Spirit's power and fight using it in the Holy Grail War.

'However, the card I have given you it's a little...different. I have left you the instructions on how to use it on the back, just channel your prana in it and you will see them.

'This will be your chance to fix your mistakes, Kiritsugu. Now, I wonder, will you use it right?

-Kischur Zelretch Schweinorg'

Kiritsugu reread the letter until it he fully processed it before looking at the card.

It had the English word 'Assassin' printed below the illustration. It was a man. Dressed in a black tunic that leaved his chest exposed, and two short swords were in his hands. The man's face was covered by an skull mask which Kiritsugu recalled that Hassan-I-Sabbah wore.

Kiritsugu had never met Zelretch in his life, but he certainly knew of him.

Kischur Zelretch Schweinorg was the sorcerer of the Second True Magic known as Kaleidoscope, the operation of parallel worlds.

It wasn't unbelievable that Zelretch was the one responsible for this, it was well known in the Clock Tower how the old vampire had a very weird definition of 'entertainment'.

Given that it was supposed to be used in a Grail War, he could only assume that the Heroic Spirit inside of it was one who classified for the Assassin class.

Kiritsugu knew that it was a literal trump card he had been given, one which he wasn't sure that he deserved.

Turning the letter over, he channeled his prana into the paper. Almost immediately words appeared on the back. Kiritsugu reread the instructions several times before burning the letter.

Taking the card in hand, Kiritsugu proceeded to walk towards the Einzbern forest, if the card was going to be an asstet, then he needed to know more about it. At the moment Kiritsugu had no idea as to what spirit was inside the card, if he wanted to use it, he needed to know how.

Once he was deep enough he decided it was time.

"Install **Assassin"**

As soon as he spoke, a surge of mana suddenly coarsed through his body, and filled him with power. At the same time, knowledge of the heroic spirits skills became clear in Kiritsugu's mind.

" _Release Install"_

As he released the card and walked back, the Mage Killer was excited. He now knew exactly which hero was in that card. It was both ironic and fitting that Kiritsugu would have it. This hero would help him tremendously in the fourth grail war. This time, he would not lose his family.

"Master Kiritsugu?" Breaking out of his thoughts Kiritsugu noticed one of the Einzbern maids, standing at the door. "The relic has arrived."

The Mage Killer nodded, he was ready to summon his Servant.

* * *

Kiritsugu looked at summoning circle inscribed in the ceramony room. He was way out of practice when it came to magic, but overall he was satisfied with it. It was time to begin.

"Is a simple ritual like this really enough to summon a Heroic Spirit?" Asked Irisviel.

"Surprisingly yes, you see, the summoning ritual doesn't require a big elaborate evocation. The actual summoning is done by the grail itself. My job as a Master is to anchor the Heroic Spirit into this world, and supply it with enough mana for it to take physical form." Explained Kiritsugu. "Iri, place the relic on the altar, that is the final step"

"Yes Kiritsugu" saying this, Iri placed Avalon in the middle of the circle. Before returning to his side.

" _For the elements silver and Iron_

" _For the foundation stone and the archduke of pacts_

" _And for my great master Scweinorg_

" _Close the four gates, come forth from the crown,_

" _and follow the forked road leading to the kingdom._

" _Fill, fill. Fill, fill fill_

" _Repeat five times but destroy each when filled_

" _Heed my words, my will creates your body, and your sword creates my destiny._

" _Of you heed the grails call, and obey my will and reason. Then answer me._

" _I hereby swear, that I shall be all the good in the world, that I shall defeat all evil in the world._

" _Thou seventh heaven clad in the three words of power, come forth from the circle of binding guardian of the scales."_

As Kiritsugu spoke, the silver circle radiated light, and as the chant came to an end, it became brighter and brighter till there was a flash.

As Kiritsugu opened his eyes, he looked through the smoke to see a familiar sillouette. Eventually the smoke cleared to show a young woman in her late teens with a slender physique, soft skin, and green eyes. She also had finely textured blond hair and wore shinging armor with a blue dress underneath.

Had Kiritsugu been an hormonal teenager and not the man he was, he would have found himself in trouble after seeing her figure. However, he was too old and tired to have such thoughts.

"I'm the Servant Saber. I ask of you, are you my Master?" She had said, repeating the words that he had once heard all those years ago.

"I am. Welcome back, King of Knights." Unlike Irisviel, he wasn't confused at all by his Servant's gender. Why would he? He had already known beforehand.

"Kiritsugu? Are you saying that-?"

"She's King Arthur?" Kiritsugu cut his wife's question in the middle of the sentence. "Of course she is. There are actually some things in the legend of King Arthur which imply that he was actually a she. This was a hunch I had, and it seems to be right." He lied through his teeth, but he had a good reason to do so.

He couldn't just say: 'Oh right I came from the future so I know everything, haha' even if he wanted to. He didn't know how the Second True Magic exactly worked, after all. There might be conditions he wasn't aware of.

Both the Servant Saber and Irisviel looked at him with curious eyes, both of them having their own reasons.

"Anyway," Kiritsugu coughed in his hand, clearing his throat. "Her gender doesn't really matter, as long as she proves to be useful." He extended his hand to her.

Saber slightly nodded in agreement, as if her Master's words were completely true to her.

He succeeded. Kiritsugu had seen how Saber insisted in that her gender never really mattered, and telling her exactly that would be a good way to start their partnership. Thanks to his future-past, Kiritsugu knew many things about the blonde swordsman, and that she preferred the Master-Servant relationship as that, a partnership, was one of those.

If he wanted to do things right this time then it was a good way to start, he supposed.

Shironak's Notes: Hey there people, you may know me for any of my fics in this Fandom, but I'm not here to make spam. And you'll ask: 'What the heck are you doing here'. Well, it's simple. I'm helping here with an idea he came up, but he certainly needed help to execute it. So, you can say that I'm the Co-author of this. Anyway, you should give this guy a chance. The thing here has potential, don't judge because all the cliché about Zelretch. See ya in the next chapter of this or the next chapter of any of my fics, whatever comes first.


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